Continuous filament mat binder system

ABSTRACT

A binder slurry for a continuous filament mat used in a phenolic pultrusion system comprising a phenolic compatible silane, a non-ionic surfactant, a defoamer, water, an organic acid and a bisphenol epoxy powdered resin having a thermally active dicyandiamide cross-linking resin. The binder slurry resin is unique in that the bisphenol epoxy powdered resin having a thermally active dicyandiamide cross-linking resin is compatable with presently available phenolic resins, and as such pultruded parts made have improved surface and mechanical properties as compared with traditional polyester type binder slurries which are not compatable with phenolic resins. Continuous filament mats made with the new binder slurry also may also be made into epoxy prepreg that can be used to make composite parts.

TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION

[0001] The present invention relates generally to continuous filamentmats and more specifically to a binder system for a continuous filamentmat.

BACKGROUND OF THE INVENTION

[0002] Continuous filament mats are widely known and are used as onecomponent in fiber reinforced composite parts.

[0003] To make a fiber reinforced phenolic resin part having acontinuous filament mat, the continuous filament mat must first beproduced. Traditionally, the continuous fiber mat is produced by firstintroducing a sizing to the continuous glass fiber by known methods. Apolyester binder system is then introduced to the sized fiber using acurtain coater or some similar technique to flood the glass fiber. Theflooded sized fiber is then dried in an oven to form the continuousfilament mat. The mat and a glass roving(s) are then subsequently wettedwith a phenolic resin, typically by running the mat and roving through aphenolic resin bath. The wetted mat and glass roving are then introducedinto a heated pultrusion die. The die shapes the mat and glass rovinginto a resin/glass composite that is then cured to form a pultrudedpart.

[0004] One problem with known methods is that the polyester bindermaterials used to form the continuous filament mats are not fullycompatible with the phenolic resins that form the resin matrix. Thisaffects the performance of the composite part.

[0005] It is thus highly desirable to make a binder system that is fullycompatible with the phenolic resin bath, thereby forming fiberreinforced phenolic resin composite parts having potentially superiorperformance characteristics.

SUMMARY OF THE INVENTION

[0006] One object of the invention is to make a binder system that isfully compatible with the phenolic resin bath, thereby forming fiberreinforced phenolic resin composite part having potentially superiorperformance characteristics.

[0007] The present invention uses a powdered bisphenol epoxy with athermally active crosslinking agent (dicyandiamide) dispersed into aflooding liquid preferably having a non-ionic surfactant, a silane, adefoaming agent, and water. An organic acid is also added for pHcontrol. The powder binder and flooding liquid act as a system to bindthe multiplicity of glass fibers into a mat. As the powdered bisphenolepoxy and thermally active crosslinking agent are compatible with thephenolic resin, as compared with traditional unsaturated polyesterbinder systems which are not compatible, pultruded parts having improvedperformance characteristics are realized.

[0008] In addition, the continuous filament mat formed in the aboveprocess could also be used in an epoxy application using a prepreg typeprocess to form a laminate material that could be subsequently pressmolded to form a composite laminate part.

[0009] Other objects and advantages of the present invention will becomeapparent upon considering the following detailed description andappended claims, and upon reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

[0010]FIG. 1 is a schematic diagram of a process for making a continuousfilament mat according to a preferred embodiment of the presentinvention;

[0011]FIG. 2 is a schematic diagram for making a pultruded compositepart from the continuous filament mat of FIG. 1 according to a preferredembodiment of the present invention; and

[0012]FIG. 3 is a schematic diagram for making an epoxy prepreg tapefrom the continuous filament mat of FIG. 1 according to anotherpreferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0013] Referring now to FIG. 1, a preferred assembly process for forminga continuous filament mat 50 is generally shown as 10. One or morestrands of a continuous filament fiber 12 are formed in a furnace 14 bymelting a quantity of glass or other reinforcing material, typically inthe form of marbles, in a manner that is well known in the art. A sizingcomposition 18 is introduced to the one or more strands of fiber 12. Thesizing composition 18 preferably contains a phenolic compatible silaneand a lubricant that is introduced to the fiber 12 by roll application,dipping, flooding or by any other method that is known in the art. Apreferred composition of the sizing composition 18 is listed below inTable 1.

[0014] The sized fibers 12 are then formed together into one continuousstrand 13 by a pair of pulleys 14A and 14B. The continuous strand 13 mayalso be split into a multiple number of bundles or splits (n=2-30), andis hereinafter referred to as continuous strand 13 for ease ofdescription. The continuous strand 13 is placed onto a moving belt 16.The continuous strand 13 is then moved along the moving belt 16 andflooded with continuous filament mat (“CFM”) binder slurry 24. The CFMbinder slurry 24 comprises a powdered polymer binder material with athermally active cross-linking agent dispersed in water with a smallpercentage of phenolic compatible silane. An antifoaming agent anddispersant are also typically added to the slurry. A preferredcomposition of the slurry is listed below in Table 2.

[0015] The CFM binder slurry 24 that is formed is then delivered from asump tank 26 to a curtain coater 28 wherein the mixture floods thecontinuous strand 13. The excess liquid is removed from the strand 13 bysuction. The strands 13 are then transferred to an oven 15 for moistureremoval and curing and then pressed in a plurality of presses 16 to forma binded filament mat 50. Preferably, the oven 15 is set betweenapproximately 450-520 degrees Fahrenheit. Upon exiting, the bindedfilament mats 50 are then slit by a slitter 30, cut to a preferred sizeby a cutter 32, and rolled onto a cardboard tube 34. The binded filamentmats 50 rolled onto the cardboard tube 34 are loaded with the CFM binderin a range of 4-8% of the dry total weight of the binder and matting.

[0016] The binded mats 50 that are formed above are then available to becombined with a plurality of glass rovings 52 to form a compositephenolic pultruded part 60. This is depicted in FIG. 2. First, the mats50 and a plurality of glass rovings 52 are dipped through a phenolicbath 54. The phenolic bath 54 that is used is well known in the art andis compatible with the mats 50 having the CFM binder. For example, onepreferred phenolic pultrusion resin for use in the phenolic pultrusionbath 30 is Georgia Pacific's 289D17 phenolic resin.

[0017] The mats 50 and rovings 52 are then introduced into a heatedpultrusion die 56. The heated pultrusion die 56 cures the resin/glasscomposite into composite part 60. The time and temperature within theheated pultrusion die 56 are to ensure that the composite part 60 formedis fully cured. Preferably, the temperature within the heated pultrusiondie 56 is between approximately 375 and 450 degrees Fahrenheit and thetime is sufficient to ensure a fully cured part.

[0018] In an alternative embodiment, the phenolic bath 54 may bereplaced with a urethane bath. The urethane resin composition, like thephenolic resin composition, is compatible with the CFM binder containedwithin the mat 50. A known urethane system useful in pultrusion includesthe Dow Fulcrum technology http://www.dow.com/fulcrum/lit.htm, availablefrom Dow Chemical of Midland, Mich. The curing temperature for theurethane composite part formed within the heated pultrusion die 56 istypically lower than that of the phenolic composite part 56, withpreferred temperatures between approximately 250 and 350 degreesFahrenheit.

[0019] In an alternative preferred embodiment, as shown in FIG. 3, anepoxy type prepreg 70 may be produced from the mats 50 formed above. Inthis process, the fibers 12 are run through the sizing composition 18and the CFM slurry bath 24 to form the binded mat 50 as described abovein FIG. 1. The mats 50 are then dipped in an epoxy bath 62 and prestagedin an oven 64 to form the epoxy prepreg 70. Preferably, the oven 64 isset for between 300 and 400 degrees Fahrenheit and the line speed is setsufficient to cure the epoxy prepreg, typically around 5-10 minutes. Thelayers of the epoxy prepreg 70 are then pressed together in a press 66to form a composite part 72. This composite part 72 may be used in awide variety of applications such as electrical laminates that are wellknown in the art.

[0020] One preferred example of an epoxy bath 62 that may be used in thepresent invention is discussed in Tables 1 and 2 of G. A. Hunter's 1988Article “Pultruding Epoxy Resin”, presented at the 43^(rd) AnnualConference sponsored by The Society of Plastics Industry, Inc., which isherein incorporated by reference.

[0021] Mat and Roving Material

[0022] The mat 50 material is preferably a continuous filament glassfiber material. This may include s-type glass fibers or e-type glassfibers, and other commercially available glass fibers that are wellknown in the art. In the preferred embodiment of the present invention,e-type glass is used.

[0023] The roving 52 material is also preferably a continuous filamentglass fiber material. This may include s-type glass fibers or e-typeglass fibers, and other commercially available glass fibers that arewell known in the art. In the preferred embodiment of the presentinvention, e-type glass is used. In addition, the method for making theglass roving material may include any method that is well known in theart.

[0024] Sizing Composition

[0025] The sizing composition 18 is made by mixing a phenolic compatiblesilane in water. The pH of the resultant mixture is then adjusted tobetween 4 and 6 by adding an acid such as acetic acid. One preferredsilane that may be used is a gamma-aminopropyl trimethoxy silane such asWitco-OSI's A-1100. At least one lubricant is added to the resultantmixture and the pH is once again adjusted to between 4 and 6 usingacetic acid. Two preferred lubricants are Cirrosol 185AE and 185AN, eachmanufactured by ICI America. Cirrosol 185AE is a octanoic (caprylic)acid-tetraethylene pentamine condensate solubulized with acetic acid,while 185AN is a nonanoic (pe/argonic) acid-tetraethylene pentaminecondensate solubulized with acetic acid. A preferred sizing composition18 is shown below in Table 1: TABLE 1 SIZING COMPOSITION 18 MIX Quantity1000 gallon Materials MIN. NOM. MAX. First Water 932 gal. 981 gal. 1030gal. Acetic Acid 9.03 lbs. 9.50 lbs. 9.98 lbs. A-1100 Silane 9.03 lbs.9.50 lbs. 9.98 lbs. Cirrasol 185AE 1.43 lbs. 1.50 lbs. 1.58 lbs.Cirrasol 185AN 0.67 lbs. 0.70 lbs. 0.74 lbs. Water for Cirrasol 3.6 lbs.4.0 lbs. 4.4 lbs. Water For Acid 560 mls. 650 mls. 740 mls. Acetic Acidfor Cirrasol 340 mls. 350 mls. 360 mls.

[0026] CFM Binder Slurry

[0027] Current binder materials use unsaturated polyester binders thathave shown unacceptable performance in phenolic pultrusion systems. Itis believed that the polyester binders do not provide a compatibleinterface with the phenolic binder resins. The CFM binder system of thepresent invention solves this problem by providing a compatibleinterface.

[0028] The CFM binder slurry 24 is prepared by dispersing a powderedpolymer resin having a thermally active cross-linking agent in water.One preferred powdered polymer resin having a thermally activecross-linking agent is a bisphenol type epoxy resin with a thermallyactive dicyandiamide cross-linking agent such as Pretex 110,manufactured by Reichold. One or more non-ionic surfactants aretypically added as a dispersant and as a defoamer. Also, a phenoliccompatible silane is added to the resultant mixture. Preferably, thissilane is Witco-OSI's A-1100 silane. Finally, the pH is adjusted tobetween 4 and 6 using acetic acid. A preferred composition of the CFMbinder slurry is shown below in Table 2: TABLE 2 CFM BINDER SLURRY 24ACTIVE NON-VOLATILE PERCENT 1000 SOLIDS AS BY WEIGHT GALLON MATERIALRECEIVED AS RECEIVED MIX Pretex 110 100 1.32% 110 Triton X-100 1000.010% 0.3 Acetic acid 0.37% 30.6 A-1100 58 0.37% 30.6 Foamex AD-300 500.010% 0.8 WATER 97.93% 8157 Total weight 100.0% 8330 MIX SOLIDS 1.55%

[0029] While the invention has been described in terms of preferredembodiments, it will be understood, of course, that the invention is notlimited thereto since modifications may be made by those skilled in theart, particularly in light of the foregoing teachings.

What is claimed is:
 1. A CFM binder slurry for a continuous filament matused in a phenolic pultrusion system comprising: a phenolic compatiblesilane; and a bisphenol epoxy powdered resin having a thermally activedicyandiamide cross-linking resin.
 2. The CFM binder slurry of claim 1further comprising a non-ionic surfactant, a defoamer, water and anorganic acid.
 3. The CFM binder slurry of claim 2, wherein said organicacid is acetic acid and wherein the pH of the CFM binder slurry ismaintained between approximately 4 and
 6. 4. The CFM binder slurry ofclaim 1, wherein said phenolic compatible silane comprises agamma-aminopropyl trimethoxy silane.
 5. The CFM binder slurry of claim4, wherein said gamma-aminopropyl trimethoxy silane is Witco-OSI A-1100.6. The CFM binder slurry of claim 1, wherein said bisphenol epoxypowdered resin having a thermally active dicyandiamide cross-linkingresin comprises Pretex
 110. 7. A method for making a continuous filamentmat, the method comprising the steps of: providing at least onecontinuous filament fiber; applying a sizing composition to each of saidat least one continuous filament fibers; forming said at least onecontinuous filament fiber into a continuous fiber strand; applying a CFMbinder to said continuous fiber strand, said CFM binder comprising aphenolic compatible silane and a powdered bisphenol epoxy powdered resinhaving a thermally active dicyandiamide cross-linking resin; and dryingand curing said CFM binder on said continuous fiber strand; pressingsaid continuous fiber strand having said CFM binder to form thecontinuous filament mat.
 8. The method of claim 6, wherein said driedCFM binder comprises between 4 and 8% of the total weight of saidcontinuous filament mat.
 9. The method of claim 6, wherein said at leastone continuous filament fiber comprises at least one continuous e-typeglass filament fiber.
 10. The method of claim 6, wherein the pH of saidsizing composition and said CFM binder slurry is between approximately 4and
 6. 11. A method for forming a pultruded composite part comprisingthe steps of: applying a sizing composition to at least one continuousfilament fiber; forming said at least one continuous filament fiber intoa continuous fiber strand; applying a CFM binder to said continuousfiber strand, said CFM binder comprising a phenolic compatible silaneand a powdered bisphenol epoxy powdered resin having a thermally activedicyandiamide cross-linking resin; and drying and curing said CFM binderon said continuous fiber strand; pressing said continuous fiber strandhaving said CFM binder; slitting and chopping said continuous filamentmat to a desired size and shape to form a continuous filament mat;pulling at least one of said continuous filament mats and at least onecontinuous filament roving through a phenolic resin bath; and moldingand curing said continuous filament mat and said at least one continuousfiber roving within a heated pultrusion die to form the pultrudedcomposite part.
 12. The method of claim 10, wherein said first amount ofsaid dried CFM binder comprises between 4 and 8% of the total weight ofsaid at least one continuous filament mats.
 13. The method of claim 10,wherein said at least one continuous filament fiber comprises at leastone continuous e-type glass filament fiber.
 14. The method of claim 10,wherein the pH of said sizing composition and said CFM binder slurry arebetween approximately 4 and
 6. 15. A method for forming a epoxy prepregcomprising the steps of: providing at least one continuous filamentfiber; applying a sizing composition to at least one continuous filamentfiber; forming said at least one continuous filament fiber into acontinuous fiber strand; applying a CFM binder to said continuous fiberstrand, said CFM binder comprising a phenolic compatible silane and apowdered bisphenol epoxy powdered resin having a thermally activedicyandiamide cross-linking resin; drying and curing said CFM binder onsaid continuous fiber strand; pressing said continuous fiber strandhaving said CFM binder; slitting and chopping said continuous filamentmat to a desired size and shape to form a continuous filament mat;pulling said continuous filament mat through a epoxy resin bath;prestaging said continuous filament mat having a quantity of said epoxyresin in an oven; and pressing said continuous filament mat having aquantity of epoxy resin to a predetermined thickness to form the epoxyprepreg.
 16. The method of claim 14, wherein said first amount of saiddried CFM binder comprises between 4 and 8% of the total weight of saidat least one continuous filament mats.
 17. The method of claim 14,wherein said at least one continuous filament fiber comprises at leastone continuous filament e-type glass fiber.
 18. The method of claim 14,wherein the pH of said sizing composition and said CFM binder slurry arebetween approximately 4 and
 6. 19. The method of claim 14 furthercomprising the step of molding a plurality of layers of the prepreg tapeto form a composite part.
 20. A method for forming a pultruded compositepart comprising the steps of: applying a sizing composition to at leastone continuous filament fiber; forming said at least one continuousfilament fiber into a continuous fiber strand; applying a CFM binder tosaid continuous fiber strand, said CFM binder comprising a phenoliccompatible silane and a powdered bisphenol epoxy powdered resin having athermally active dicyandiamide cross-linking resin; and drying andcuring said CFM binder on said continuous fiber strand; pressing saidcontinuous fiber strand having said CFM binder; slitting and choppingsaid continuous filament mat to a desired size and shape to form acontinuous filament mat; pulling at least one of said continuousfilament mats and at least one continuous filament roving through aurethane resin bath; and molding and curing said continuous filament matand said at least one continuous fiber roving within a heated pultrusiondie to form the pultruded composite part.